The one I've not discovered yet!
Not a secret mode, but there is a secret BONUS for finishing the Save Nell mode super fast in Rocky and Bullwinkle. It's almost impossible, but if you can get all 5 drops down within a second or two it either lights extra ball or, if you don't have any more extra balls available, it gives you an extra 25M. I doubt this can be done in single ball play and it would be incredibly difficult in multiball (I have never done it with the glass on).
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